Sometimes, a knee replacement may not work correctly. There is a wide range of reasons that a knee replacement may not work. Some of the most common reasons include: loosening of the parts, infection, instability of the joint, fracture of the bone, stiffness, knee cap problems, and allergic reactions. A second surgery, also known as a revision surgery, may be required to fix the problem. A revision knee replacement is also known as a revision knee arthroplasty. The revision surgery may require replacing one or several of the parts from the prior knee replacement. In the case of very complicated problems like infections, more than one revision surgery may be necessary to adequately fix the problem. Revision surgery generally requires a short hospital stay.